In case where it is desirable to feed a given amount of water into a reservoir and so forth, it has been customary to use a pump.
In case where water is fed through a pump, there is no difficulty in controlling the rate of flow of the water. This is not the case, however, where the water is pure water or ultra pure water. Then, a pump is not suitable for use in feeding the water.
This is attributed to the fact that pure water unlike normal water does not contain an impurity which serves to provide a lubricating function for a sliding surface contained in a pump and so forth. Thus, if pure water is fed through a unit, such as a customary pump, which involves a mechanical friction, there has been encountered the problem that the pump or the like unit is low in its durability and does cause the pure water to be contaminated due to a wear of a component thereof. Should the pure water be ever fed through the pump or the like, a prohibitively large feed equipment would be required, and its system and operation would be prohibitively costly.
Besides, in this conjunction, while a tube pump is non-contaminative to pure water, it must be taken into account that the same is poor in its durability and in addition is inconvenient in that a pulsation takes place unavoidably.
Furthermore, in case where a unit for feeding water through a pump is used with a humidifier unit in which a heating wire made up from a metal or the like is brought into direct contact with water, the problem is brought about that an electrical leakage may sometimes take place externally via the pure water. Thus, pure water (with its resistance value of 18 ohm) is by no means an insulator and, if carbon dioxide in the air is absorbed therein, it will have its resistance value further reduced to one tenth. Hence, the problem of an electrical leakage tends always to be brought about.
An air conditioning apparatus of the conventional design has been constructed as shown, for example, in Japanese Unexamined Patent Publication No. Hei 02-1113. Thus, it typically comprises a cooling dehumidifier unit for cooling an intake air flow to dehumidify the cooled air flow, a heating unit for heating to a predetermined temperature the air flow that has been dehumidified by the cooling dehumidifier unit, a humidifier unit for humidifying the resulting air flow to a predetermined humidity and an air blower unit for feeding the humidified air flow.
And, in the conventional air conditioning apparatus, the air blower unit, the cooling dehumidifier unit that comprises a heat exchanger for a cooling purpose, the heating unit that comprises a heat exchanger designed to adjust the air temperature, and the humidifier unit are successively arranged in a vertical direction within a cylindrical housing so that a vertical laminar flow of which the temperature and the humidity are controlled may be fed to an area to be air conditioned, such as a spin coating system as mentioned above, that is positioned downwards of these components.
In an conventional air conditioning apparatus as mentioned above, however, it must be noted that the water which is removed from the air and condensed at the cooling dehumidifier unit has no way but to be allowed to drop downwards and, if this water happens to adhere onto a temperature and humidity sensor which is provided in the heating unit or the housing, it follows that an accuracy at which the temperature and the humidity are controlled could significantly be lowered. Also, if the above mentioned water happens to get mixed with the conditioned air flow to adhere onto a filter that is provided at an outlet of the housing, the problem has arisen that the filter may be clogged, thus significantly lowering the rate of the air flow being fed.
It is a first object of the present invention to provide a water feed device for humidification, which eliminates a need for a mechanical water feed unit, is capable of feeding a given quantity of pure water into an evaporation zone in an inexpensive arrangement, and may not generate an accident due to the electrical leakage.
Also, it is a second object of the present invention to provide an air conditioning apparatus whereby if water droplets happen to fall by gravity from any of a variety of the components of an air conditioning system including the cooling dehumidifier, they could not adhere onto the heating unit or the temperature and humidity sensing means which are provided in the housing and could not be introduced into the conditioned air flow at the outlet side to produce a clogging of the filter or to induce any other adverse effect; there could be no influence from the moisture condensed water at all; and an increased precision at which a temperature and a humidity are controllable is assured.